Electronic Components Circuit/Schematic Symbols

RESISTOR Resistors restrict the flow of electric current, for example a resistor is placed in series with a light- emitting diode (LED) to limit the current passing through the LED.

CAPACITORS Capacitors store electric charge. They are used with resistors in timing circuits because it takes time for a capacitor to fill with charge. timing circuits

DIODES Diodes allow electricity to flow in only one direction. The arrow of the circuit symbol shows the direction in which the current can flow. Diodes are the electrical version of a valve and early diodes were actually called valves.

TRANSISTOR Transistors amplify current, for example they can be used to amplify the small output current from a logic chip so that it can operate a lamp, relay or other high current device. In many circuits a resistor is used to convert the changing current to a changing voltage, so the transistor is being used to amplify voltage.

SWITCH A simple on-off switch. This type can be used to switch the power supply to a circuit.

SPEAKER Loudspeakers are output transducers which convert an electrical signal to sound. Usually they are called 'speakers'. They require a driver circuit, such as a 555 astable or an audio amplifier, to provide a signal

LAMP Lamps emit light when an electric current passes through them

TRANSFORMERS & COILS Transformers convert AC electricity from one voltage to another with little loss of power. Transformers work only with AC

BATTERY Supplies electrical energy. A battery is more than one cell.

VACUUM TUBES The function of a vacuum tube is to switch or amplify electricity

INTEGRATED CIRCUITS (IC) Integrated Circuits are usually called ICs or chips. They are complex circuits which have been etched onto tiny chips of semiconductor (silicon). The chip is packaged in a plastic holder with pins spaced on a 0.1" (2.54mm) grid which will fit the holes on stripboard and breadboards. Very fine wires inside the package link the chip to the pins.

VOLTAGE REGULATOR A Voltage Regulator (also called a "regulator") has only three legs and appears to be a comparatively simple device but it is actually a very complex integrated circuit. A regulator converts varying input voltage and produces a constant "regulated" output voltage. A regulator converts varying input voltage and produces a constant "regulated" output voltage. Voltage regulators are available in a variety of outputs, typically 5 volts, 9 volts and 12 volts. The last two digits in the name indicate the output voltage. LM volts The last two digits in the name indicate the output voltage. LM volts